To investigate the effect of higher order aberrations, and spherical aberration (SA) in particular, on the distance corrected near vision (DCNV) and contrast sensitivity (CS) in presbyopic patients.

Methods:

This was a retrospective analysis of consecutive presbyopic patients after Laser Blended Vision (LBV) using the MEL80 excimer laser and VisuMax femtosecond laser (Carl Zeiss Meditec) with all ablations centered on the corneal vertex. Inclusion criteria were presbyopia (defined as DCNV J7 or worse), age 55-65 years, and CDVA 20/20 or better. Monocular DCNV was measured using a near vision reading card with full manifest distance correction through a phoropter. All WASCA wavefront scans were analysed in a 6-mm analysis zone following tropicamide. CS was measured using the CSV-1000 (VectorVision). Eyes were grouped into myopia and hyperopia. Correlations were performed between post-op SA and post-op DCNV, between post-op higher order RMS (HORMS) and post-op DCNV, and between post-op HORMS and change in CS.

Results:

The study included 96 myopic eyes (mean SEQ -4.19±2.29D) and 341 hyperopic eyes (mean SEQ +2.46±1.26D). Mean DCNV improved by 0.71±1.45 lines in the myopic group (p<0.001) and by 0.85±1.40 lines in the hyperopic group (p<0.001) after treatment. In the myopic group, DCNV was better for higher SA (R2=0.047, p=0.035), and higher HORMS (R2=0.046, p=0.031). In the hyperopic group, DCNV was not directly correlated to SA (R2=0.008, p=0.100), however DCNV was better for higher HORMS (R2=0.045, p<0.001). There was no statistically significant change in CS at 3, 6, 12 or 18 cpd in either group. In the myopic group, the CS was not changed by increasing HORMS, while in the hyperopic group, there was a small reduction of 1 CS patch per 0.88 μm HORMS at 12 cpd and 1 CS patch per 0.71 μm HORMS at 18 cpd.

Conclusions:

DCNV was increased by approximately one line in both myopic and hyperopic eyes after LBV. Increased HORMS was found to improve DCNV in both myopia and hyperopia and SA was correlated with DCNV for myopia. In hyperopia, the finding that the correlation between DCNV and SA was not statistically significant might be explained by larger angle kappas and the fact that wavefront measurements are conventionally calculated about the entrance pupil center, whereas the ablation was centered on the corneal vertex, meaning that spherical aberration would produce ‘wavefront coma’. Further analysis based on corneal topographic wavefront changes would be of interest.